'White whale' discovered in depths of the Smithsonian

In this reconstruction, a pod of Albicetus travel together through the Miocene Pacific Ocean, surfacing occasionally to breathe. Modern sperm whales are also known for forming these tight-knit groups, composed mainly of females and their calves. (Credit: A. Boersma)

It's quite the epic timeline: Some 15 million years ago, the creature swam in our oceans. In the 1880s, its remains were found in California. In 1925, Remington Kellogg classified it in an extinct genus of walrus.

Now, nine decades later, researchers with the Smithsonian's National Museum of Natural History say the fossil has been rediscovered—as a white whale. As Smithsonian reports, Kellogg based his walrus assumption on the skull's large tooth.

But the specimen's true identity came to light thanks to marine mammals curator Nicholas Pyenson, who 10 years ago as a student "made a trip to the Smithsonian, and there was this big skull..." Realizing nothing had been published on it since 1925, he and Alexandra Boersma dug in and soon found they had on their hands something new, as they described Wednesday in PLOS One: the Albicetus oxymycterus. As a press release explains, the new genus of ancient sperm whale, Albicetus, means "white whale," a name that's a nod to Moby Dick and so given thanks to the fossil's bone-white color.

As for that tooth, PLOS Blogs reports that the sperm whale is not only toothed, but the largest toothed predator currently living. But it features just one set of bottom teeth, used primarily for seizing or tearing prey, while the fossil features an upper row.

It's possible, then, that the ancient version ate seals or smaller whales, something today's sperm whales don't do (they mainly swallow squid whole). Per Boersma, the ancient teeth indicate an evolutionary shift; "they changed their feeding strategy." Another evolutionary change: Though modern sperm whales reach some 60 feet in length, the Albicetus oxymycterus is believed to have been at most a third that long, notes Smithsonian.